Webinar «International electrotechnical standard IEC 62305. Protection of electrical and electronic systems», page 3

— And this level of immunity is based on the choice of systems limiting pulse voltages, which correspond to the protection level and it should correspond to the level of pulse voltage the equipment can stand. Level of equipment ruggedness should be higher than protection level. This different is not obligatory for execution, if we have additional voltage surges and drops of connecting conductors, systems of surge protective devices - it means that the values of protection level should be higher, than U delta. There are different systems of surge protective devices - limiting or switching. For a switching type, the system of surge protective devices uses. We need to remember here, that there is a nominal level of fata given by the manufacturers. And it all refers to the question or Mr. who asked about the distance in meters.

— As concerns coordination of surge protective devices system, it is the first picture - for the limiting type of surge protective devices system. Here the distance should be 10,20, 50 meters. Induction here is about one micron. Depending on the current value, there can be voltage drop and when we install the second system of surge protective devices, protection of electronic and electrical equipment is higher. If we need to coordinate two types of surge protective devices, using electrical arresters, for example, as shown in picture two and the system of surge protective devices metal oxide variable resistors. There are manufacturers, who offer surge protection device systems to contain electrical arresters and they should be integrated into the system. There are cases, when the protected side of equipment depends on the lines entry point. There are examples of coordination of surge protective devices system and we have two variants.

— The second part of surge protective devices system should be close to the equipment in order to reduce the risk of voltage drop, especially at the border. And the second - distributing, use of a distribution board. There is a possibility to install surge protective device system of Class 2 or SPD, which is tested by two types of classes. Also SPD which is tested with the use of a united wave - it is test of Class 3. It is a very complex formula which should be used at the construction. Cass 1 and Class 2, they can be used depending on the required protection level, level of surge protection device. And depending on the location of surge protection device system.

— There are four types of damage, threat. The first one - is a lightning strike into a structure or building, and the second, is damage due a lightning strike near the building, the third type - is a strike into lines connected to the building and the fourth type is a strike near the lines connected to the building. Depending on a lightning strike, we need to determine SPD location points. We need to put SPDs on low voltage or high voltage lines, near transformers and put them at the entry to the building, which is very important.

— As concerns TN-C systems, grounding systems, then there is an example where to install SPD, what SPDs can be used. Type 1 - near the building, type 2, type 3 - directly at the equipment to be protected. The installation depends on the type of low-voltage system.

— We are a bit late again, if you want, we can stop and talk about the questions on the surge protective device system. We see a question from Mr.Zakharov:" Is it possible to install SPB not at the entry to the building, but bring the cable to the protected equipment, located in the board and install SPD there?"

— «If you have SPD and lightning protection zones, then SPD must be installed at the entry to the building?»

— Here are other variants how to do it. In the concept of zoning lightning protection zones. Here SPD systems are used on the inputs and lines to the equipment or they are used together with shielded cables and wiring ducts. On the second picture we see a zone, a large non-shielded zone 2 and there is SPD installed at the entry to the building or room. All installations, all lines should be shielded- signal lines, power lines. SPD here is in red colour. We also see that we need to create lightning protection zones 2. We install a shield in different rooms, on different floors of the building and we install these shields by using, for example, special coatings or metal details, constructions, fittings or by installation of metal cells. In such cases, we have a need to install SPD only at the inputs. Signal lines will be used with a separating transformer. There are shields inside it, which minimize high-frequency pulses.

— And here there is a table, we see the steps, what actions we need to make and who should make them. First, we need to estimate the risk, estimate protection method, protection level and after that, we need to analyse the cost of chosen protection measures. Understand, what is required for the chosen level of lightning protection? Where these zones will be? Where the boundaries will be? After that, we need to define methods of shielding, grounding, potential equalization, routing of cables, systems of surges limitations, insulating surfaces, schemes, images, installation, documentation, sketches, checks, documenting of installations and determination of adequacy of chosen measures of lightning protection. And for large buildings it is most important, for special buildings, some industrial or telecommunication buildings.

— It is a joke, it is written on the picture: the lecturer says:" By the way, a lightning hit out database, can you work 30 hours more, please?" I hope you won't have such a situation very often. It's a joke. Thanks very much for your attention. If you have any questions, I can of course answer them. One question from Mr. Norenko. Please give me time to read it. The question refers to the requirements of resistance of functional grounding. Of course, they depend on the type of installation, type of equipment. Usually, when we have a substation, electric substation inside the building or near the building, then the value of the functional grounding depends on the power of the transporter. There are requirements; they are given in this standard. There is a system of functional grounding, if is should execute requirements of lightning protection, then it is necessary to execute both requirements and you remember that there are requirements for electric installations, which refer to the safety from electric shock.